Surgical scalpels are a class of knives which are manufactured in accordance with particular stringent standards, in order to assure their quality and precision of handling. It goes without saying that the blade of the knife must be sharp and of the finest quality, but the entire instrument must be of such a weight and size as to fit well and be comfortable within the hand of the surgeon. In addition, it must be well-balanced, to be capable of precise manipulation, and it must be small enough so as not to obstruct the surgeon's view of the blade while in use.
In the sometimes harried atmosphere of an operating room, a surgeon must often work quickly, handing instruments back and forth to assistants. With sharp implements, such as scalpels, the danger of accidental cutting or jabbing of operating room personnel is ever present. Furthermore, certain fatal infections, such as the AIDS virus can be transferred to individuals through minor cuts, when even small quantities of blood are mixed. In a sense, a minor operating room injury can ultimately prove to be fatal.
Scalpels have been provided with removable guards to prevent contact with the blade when not in use. For example, U.S. Pat. No. 4,735,202 issued to R.W. Williams on Apr. 5, 1988 discloses a scalpel in which the blade guard is provided in the form of a sleeve which is slidably mounted over the scalpel and may be locked into position over the blade when not in use. Although such a blade guard could be used effectively prior to starting and after completing a surgical procedure, it could normally not be used and would be of no value during the procedure itself. A primary reason is that two hands are required to position the blade guard, and the surgeon typically has only on hand available for the scalpel during the procedure. Furthermore, even if the surgeon were able to use both hands, the scalpel would be unacceptable, because the surgeon's attention is distracted from the procedure whenever he must handled the scalpel. In addition, the surgeon risks injuring himself with the scalpel every time he must bring his second hand into use. Thus, the scalpel disclosed in this patent would be used in the open position during an entire surgical procedure and, for all intents and purposes, the blade guard is unavailable during the procedure. Various types of utilities knives have been provided with blade guards that slide from a blade-guarded position to a blade-exposed position by manually operating a lever which is coupled to the blade guard so that the pivoting movement of the lever is converted to the sliding movement of the blade guard. Such knives are disclosed in U.S. Pat. No. 4,757,612 issued Jul. 19, 1988 to Peyrot and U.S. Pat. No. 2,380,787 issued Jul. 31, 1945 to Pierce et al. These knives have the advantage that the guard operating lever is operated by the same hand which holds the knife and, therefore, the blade guard may be moved in and out of position in a single-handed operation.
However, such utilities knives are gripped in the hand of the operator in a manner similar to a tennis racket. Surgical scalpels, on the other hand, are held between the fingers delicately, in a manner similar to a pencil. Thus, while the utility knives may be operated in the manner of a bicycle hand brake, the scalpel can only be pressed between the thumb and the forefinger, and the range of manual movement available to operate it is substantially less, on the order of one-quarter to one-half inch. On the other hand, it is essential that the blade guard be moved clear of the scalpel blade when the scalpel is being used, in order that the surgeon's view of the blade be entirely unobstructed. Typically, this requires that the blade guard move over a distance at least as great as an inch. In addition, it is essential that the blade guard be operated without changing position of the hand. That is, the blade guard must be operated while maintaining the hand in the position in which a scalpel is normally held. Otherwise, it could interfere with the surgical procedure. In addition, the pressure required to operate the blade guard should be no greater than the finger pressure required to hold the scalpel, in order to avoid fatigue and cramping of the surgeon's hand.
Broadly, it is an object of the present invention to provide a scalpel with a protective blade guard which can be operated by the hand holding the scalpel so as to move the guard between a blade-guarded and a blade-exposed position. It is specifically intended that the blade guard be so moved when the scalpel is grasped in its position of normal use.
It is another object of the present invention to provide a scalpel with an automatically retractable blade guard which fits well and comfortably within the hand of the surgeon, is capable of precise manipulation, and does not obstruct the surgeon's view of the blade while in use.
It is another object of the present invention to provide a scalpel with a retractable blade guard in which the finger pressure required to retract the guard is comparable to the finger pressure required to hold the scalpel while in use.
It is another object of the present invention to provide a scalpel with a retractable blade guard in which the distance moved by the fingers of the surgeon while moving the blade guard between blade-exposed and blade-guarded positions is substantially less than the distance moved by the blade guard between these positions.
It is also an object of the present invention to provide a scalpel with a retractable blade guard which is simple and convenient in use and relatively inexpensive in construction.
In accordance with the present invention, a scalpel is provided with a blade guard which is mounted for movement between a blade-guarded position and a blade-exposed position and an actuating mechanism for the blade guard is positioned in such a way that the fingers of the surgeon automatically engage the mechanism when the scalpel is held in its normal position of use. The actuating mechanism is coupled to the blade guard through a linkage assembly which causes the blade guard to move over a substantially greater distance than the distance which the surgeon's fingers move in operating the actuating mechanism. In a preferred embodiment, the blade guard slides over a linear path, the actuating mechanism comprises a tongue-like structure integral with the scalpel, and the linkage assembly comprises a plurality of pivotally interconnected lever arms. One of the lever arms is positioned so as to be captured in a detent mechanism when the blade guard is fully retracted to its blade-exposed position.